In a context of increasing world energy demand, capture of carbon dioxide for sequestration thereof has become an imperative necessity in order to limit greenhouse gas emissions harmful to the environment. The Chemical Looping Combustion (CLC) method allows to produce energy from hydrocarbon-containing fuels while facilitating capture of the carbon dioxide emitted during the combustion.
An oxygen carrier (metallic oxide) is used for continuous transfer of the oxygen from the “air reactor” or “oxidation reactor” (RO) to the “fuel reactor” or “combustion reactor” or “reduction reactor” (RR) where the oxygen is provided to the fuel. Thus, direct contact between the air and the fuel is prevented. The resulting gas is rich in CO2 and it is not diluted with nitrogen. It can thus be compressed and stored after simple condensation of the water produced. The reduced oxygen carrier (Me) is then sent to the air reactor in order to be reoxidized (to MeO), thus forming a chemical loop.
Solid fuels having a high carbon to hydrogen ratio produce large amounts of greenhouse gas. Thus, the combustion of solid fuels is a particularly interesting application for the CLC method. Various CLC configurations have already been developed and tested on the laboratory scale for the combustion of solids. However, additional research work is necessary to guarantee the feasibility of the method. The most important technological challenges for the CLC method with solid feedstocks relate to the solid—solid separation (oxygen carrier—unburnt solid fuel) and to the high-pressure operation of the method.
In order to overcome the aforementioned drawbacks, a new system is provided for burning (and/or gasifying) a solid fuel without direct contact between the oxygen carrier and the fuel.